The present invention relates to multibeam satellites and, more particularly, to multibeam satellites having reconfigurable beam coverage and frequency channelization.
Communication satellites in geosynchronous orbit generally function as a simple repeater operating in bent-pipe mode. The only signal processing is a frequency translation between the uplink and the downlink channels, with the signal modulation remaining unchanged. In order to provide a high degree of capacity and to serve a diverse set of users, multiple transmit and/or receive beams are often employed.
In these multibeam satellites, incoming beams carry individual modulated carriers that may be switched among several downlink beams. A typical communications satellite includes an input demultiplexer that separates signals into one or more specific frequency bands to be amplified for retransmission to the ground in each of a number of individual transponders. The routing of signals within the satellite payload is generally unique for each payload design and is not able to be changed except for specific switching options that are included in the initial design of the unique payload. Furthermore, the specific frequency plan typically depends on the geosynchronous orbit location of the satellite due to the assignment of different frequencies according to ITU (International Telecommunications Union) standards.
With the expanding applications of satellites for many different aspects of communications, market requirements are continuously changing. As a result, a fixed payload configuration may not be able to meet coverage or channelization requirements that differ significantly from the original design. Accordingly, it would be highly desirable for a multibeam satellite to be capable of varying the frequency channel plan in which the number of channels, the channel bandwidth, the channel center frequency, and the channel loading are fully reconfigurable.
Because of the continuously changing market requirements, a multibeam satellite must also be capable of adapting to changes in the location of the requests for service. Thus, antennas on multibeam satellites must also be capable of reconfigurable beam coverages.
A multibeam satellite having a reconfigurable multibeam phased array antenna is an ideal solution to the ever-changing beam coverage requirements. Such a satellite should be capable of reconfiguring the location of the beams, the size of the beams, and the power radiated in each beam.
Accordingly, it is an object of the present invention to provide a multibeam satellite having reconfigurable beam coverages, beam power, and frequency channels along with dynamic frequency channel assignment.
It is a further object of the present invention to provide a multibeam satellite having a reconfigurable communications payload which can route any channel from any input beam to any channel of any output beam and which can reconfigure the number of channels, the channel bandwidths, the channel center frequencies and guard-bands, and the channel filter shapes.
It is a further object of the present invention to provide a multibeam satellite having a reconfigurable communications payload which can route any channel from any input beam and then cross-band to any channel of any output beam of different payloads and frequency bands.
It is a further object of the present invention to provide a multibeam satellite having a reconfigurable communications payload which can route any channel from any input beam and then Inter-Satellite link (ISL) to any channel of any output beam of a different satellite.
It is a further object of the present invention to provide a multibeam satellite having the capability for dynamic reconfiguration of the gain contour within each beam, allowing for increased efficiency in allocating satellite power to compensate for changing rain attenuation effects.
In carrying out the above objects and other objects, the present invention provides a satellite subsystem employing a reconfigurable communications payload and phased array antennas to accomplish a reconfigurable satellite regardless of geographical location. The satellite subsystem provides universal antenna pattern shaping capability along with an ultra flexible channel switching for desired signal path, filters, and bandwidth.
The satellite subsystem includes a receive antenna having a reconfigurable beam forming network for forming input beam signals from input signals received by the receive antenna from sources. An input switch matrix power divides the input beam signals into sets of input beam signals. The satellite subsystem further includes a channelizer having a plurality of channel processors each receiving at least one input beam signal from the input switch matrix. The channel processors filter the input beam signals into channel signals. Each of the channel signals corresponds to a respective channel of the input beam signals. The channel processors change the frequency of a channel signal to route the channel signal to a different channel than the respective channel of the input beam signals. An output switch matrix combines the channel signals into output beam signals. Each of the channel signals corresponds to a respective channel of the output beam signals. A transmit antenna having a reconfigurable beam forming network forms output signals from the output beam signals for transmission by the transmit antenna to destinations.
In accordance with the subsystem of the present invention, a method of routing a channel of an input beam signal to a channel of an output beam signal is also provided.
The advantages of the present invention are numerous. The satellite subsystem provides for the in-orbit reconfigurability of all parameters associated with conventional transponder satellite design, namely: variable frequency plan (number of channels, channel bandwidth, center frequency, filter shape, and channel gain/loading), variable beam coverage shape and antenna gain, variable transmit power per downlink beam coverage, and the addition of on-board switching/routing of individual channels between multiple uplink, downlink, and crosslink (ISL) beams. The satellite subsystem is flexible to adapt in orbit to support a wide range of geographical locations or business applications.